The subject invention is directed toward the fastener art and, more particularly, to a molded plastic, push-in type fastener.
The invention is especially concerned with a fastener that comprises a relatively rigid, elongated body having a head or closing part at one end and carrying two resilient, springy arms on diametrically opposite sides of the other end to extend outwardly at an angle to each other. The free ends of the arms have notches or catches such that when the fastener is pushed through workpiece opening, the catches engage the underside of the opening to retain the fastener in the workpiece.
Fasteners of this general type are known in the prior art. For example, U.S. Pat. No. 3,909,883 shows a fastener in which two resilient arms, after being positioned in a workpiece opening, are clamped to the workpiece to thereby fasten other parts to the workpiece. A disadvantage with this known construction is that the spacing between the head and the springy arms must be so dimensioned that a secure holding results only through a very slight tolerance range of workpiece thickness. If the workpiece has too great or too small a thickness, the holding acting of this prior fastener is greatly reduced. Moreover, the construction is such that two workpieces or plates, provided with openings, cannot be readily aligned or securely joined.
Also known in the prior art is a one-piece fastening element of plastic, which is designed as a self-centering "fir tree" clip. In this known construction, shown in West German published application No. 3,014,745, the body of the fastening element has several stays or fins, positioned one above the other, so that two or more workpieces each provided with an opening, can be joined together. A disadvantage here is that with lateral displacement of the openings, the fastening element cannot bring them into alignment. Thus, the danger of a misaligned installation cannot be excluded. Moreover, this known fastener is relatively expensive to manufacture.
Also belonging to the state of the art is a plastic fastener for the detachable fastening of functional or constructional parts on support plates, such as, for example, the body or frame components of a motor vehicle. As shown in West German published application No. 3,040,360, this fastener comprises a head part and a solid core shaft with several flexible lamella, standing out radially therefrom. This construction is also costly to manufacture, and is unable, in case of a lateral displacement of workpiece openings, to make a functionally correct lateral adjustment of the openings during mounting of the fastener.